1. Technical Field
This invention relates generally to lighting assemblies. More particularly, it relates to LED light module assemblies. Most particularly, it relates to LED light module assemblies for high-power LED arrays having controlled thermal pathways and heat sinks to remove the heat generated by operation of the LED's and associated electronics.
2. Related Art
Lighting modules which utilize light emitting diodes (LED) as light sources are used currently in a wide variety of lighting applications, including automotive applications. Because of their ability to provide a relatively high light output per unit area and their ability to be flexibly arranged into modular light arrays of various configurations, the commercial demand for LED light module assemblies is currently increasing.
Of particular interest is the development and recent commercial availability of higher light output, higher power LED's, such as those made from InGaAlP or InGaN semiconductor materials which use power in the range of 1-5 W and higher. These high power, high light output LED's typically have recommended temperature operating limits. One of these limits is specified with respect to the maximum temperature of the p-n junction that makes up the LED, and is referred to as the junction temperature. For example, in the case of one commercially available InGaAlP LED device, the maximum junction temperature (Tj) is specified as 125° C. Other LED devices made using different semiconductor materials and/or processing methods have different but similar operating temperature limits. While significant advances have been made in improving the light output and reducing the size of LED's, their commercialization has been somewhat limited in part by difficulties associated with the removal of the increased amounts of heat generated by these higher power devices using existing electronics packaging technology and lighting module designs. Presently, such LED's are generally packaged into lighting modules using standard G10/FR4, CEM and other printed circuit board materials and their associated component packaging and bonding technologies, without the use of heat sinks or other means of removing the increased amounts of heat from the modules and improving the thermal management and control of the lighting modules.
In addition to the increased power consumption of the LED's, there is also a desire to increase the packaging density of the LED's on the circuit boards into ever denser arrays and other configurations, which correspond to higher light outputs per unit area, but also increase the power densities and operating temperatures of these devices, and further compounds the problems associated with thermal management of lighting modules which incorporate them and maintaining the necessary operating limits, such as Tj. This is particularly the case for high density LED arrays. However, increases in packaging density have been limited by the thermal management issues described above.
In addition to the limitations associated with packaging high power, high density LED's described above, the current state-of-the-art of electronic packaging technology for LED's used in lighting module applications is not particularly well adapted for handling and assembly using high volume assembly methods. For example, surface mounting with reflow soldering of the LED's on the circuit boards using standard techniques is either currently not feasible and/or extremely difficult with many of these newly released LED high power packages. Additionally, high volume automation and integration of the aforementioned thermal pathways and/or heat sinks into, through, and around the LED lighting modules have not been demonstrated in large scale to date.
Therefore, it is desirable to overcome the limitations of the related art LED lighting module assemblies.